On 2019-10-28 23:41, PG Doc comments form wrote:
> The following documentation comment has been logged on the website:
>
> Page: https://www.postgresql.org/docs/12/ddl-generated-columns.html
> Description:
>
> https://www.postgresql.org/docs/12/ddl-generated-columns.html
>
> In the below
> "Consider the differences between a column with a default and a generated
> column. The column default is evaluated once when the row is first inserted
> if no other value was provided; a generated column is updated whenever the
> row changes and cannot be overridden. A column default may not refer to
> other columns of the table; a generation expression would normally do so. A
> column default can use volatile functions, for example random() or functions
> referring to the current time; this is not allowed for generated columns."
>
> "a generation expression would normally do so" should be changed to "a
> generated column" for easier reading
The current wording seems more precise. It's the expression that does
the referencing, not the column itself. There could be other things
attached to a column to could reference other things or not.
--
Peter Eisentraut http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services